1. Field of the Invention
The invention relates to communications systems and, more particularly, to Digital Subscriber Line (DSL) communications.
2. Description of the Related Art
DSL is a digital form of data communications that dramatically increases the digital capacity of ordinary telephone lines or the local loops into homes or offices. Digital communication is the exchange of information in binary form. Unlike an analog signal, a digital signal does not use continuous waves to transmit information. Instead, DSL transmits data using discrete signals, for example, on and off states of electrical current.
DSL provides an always-on operation in which digital data does not travel through the Public Switched Telephone Network (PSTN). Instead, at the Central Office (CO), digital data is aggregated and forwarded to an appropriate Internet Service Provider (ISP) or data network.
There are several varieties of DSL. High Bit Rate DSL (HDSL) is a symmetric technology, which provides the same transmission rate in both downstream and upstream directions. Symmetric DSL (SDSL) is an HDSL variation that uses only one cable pair and is offered in a wide range of speeds from 144 Kbps to 1.5 Mbps. SDSL is a rate adaptive technology. Asymmetric DSL (“ADSL”) is a DSL flavor that shares the same line as the telephone, since it uses higher frequencies than the voice band. A version of ADSL is known as G.lite. Other varieties of DSL can include Rate Adaptive DSL (RADSL) that adjusts speed based on line quality, Very High Bit Rate DSL (VDSL) that is an asymmetric version used as the final drop from a fiber optic junction, and ISDN DSL (IDSL). The specifications for these and other flavors of DSL are hereby incorporated by reference.
From time to time, a DSL line may become out of sync with the CO or DSL modem within a DSL operation center and fail to work. Such failures can occur up to several times per month. These failures manifest themselves to users as a loss of service, or more particularly, as a loss of the ability to connect to the Internet. When such failures occur, the user may think that the computer or the DSL modem are responsible for the problem. As a result, the user may try to implement corrective action such as changing computer system and/or DSL modem settings or calling a helpline. This can frustrate users as the source of the problem is not the computer system or the DSL modem, but rather the DSL line itself. The user is effectively diverted from determining the actual source of the problem.